The PEAR Coding Standards apply to code that is part of the official
PEAR distribution. Coding standards often abbreviated as CS among
developers and they aim to keep code consistent to be easily readable
and maintainable by most of PEAR folks.

The original coding standards have been adjusted several times through
RFCs:

Rules, rules and more rules. I can understand the length. Tabs, on the other hand, pl--ease - I like to see the code without scrolling or wrapping. As long as the tabs are noticeable and well placed, two spaces per tab is ideal = easily read.

From the PEP 8 -- Style Guide for Python Code about maximum line length:

"Limit all lines to a maximum of 79 characters.

There are still many devices around that are limited to 80 character
lines; plus, limiting windows to 80 characters makes it possible to have
several windows side-by-side. The default wrapping on such devices
disrupts the visual structure of the code, making it more difficult to
understand. Therefore, please limit all lines to a maximum of 79
characters. For flowing long blocks of text (docstrings or comments),
limiting the length to 72 characters is recommended."

The suggestion on line lengths is only partly due to terminal considerations. Readability of code is also a very important issue. It's not about setting a precise limit for the sake of consistency so much as giving a guideline to make sure that your code is easily readable both by yourself and others who must follow it later.